<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>CSS特性-层叠性</title>
  <style>
    /* 覆盖；叠加 */

    div {
      color: green;
      font-size: 30px;
    }

    div {
      color: red;
      font-weight: 700;
    }
  </style>
</head>
<body>
  <div>div 标签</div>
</body>
</html>